Finally, Battery level is callibrated, sleep mode activated (when on power usage is around 60mA and in sleep mode around 10mA, still a lot, but I'll think about relay switch to completely isolate batteries from unit).Today I fixed Signal Bar, so this is not just picture displayed on the screen. Took whole day to figure out algorithm and redo the code to get it working!Here is it:Transmitter sends signal, receiver receives it, then after reading sensors, sending the row of values back to the receiver. On the receiver I've arranged 2 time measurements, one - time1 to read lost signal (packet has not being received) and time unit is up, difference will give me idea how long interruption occure, based on set timeframe boxes will appear on the signal bar, full 6 boxes and G letter, which means that the signal is strong and there were no interruption and lowest, when there are no replies for 1 second (1000 milliseconds) will indicate Lost Signal! mark next to the antenna on the screen. Well I do not know how else I can indicate signal other than that? any ideas will be highly appreciated.Right now it looks like OK, when I go to the next room, where signal is not so strong, signal bar starts playing around, only the issue I can see is fluctuations are not smooth, but I think it's because of instant reading, if I set local delay I guess it'll get better something like this:

not to read and display signal level every loop, but maybe once in the 30sec?

Other thing is, I used nRF24L01 module, but do not really appreciate it's signal strength, it's quite short, what is available to rather increase the distance or any known replacement would be highly appreciated?Who can suggest? I need something stronger to have control over couple kilometers around!

Other question would be, can I use theese modules to transmit clear voice and videostream?

Well do not know how yet, but I want to hook up all through Arduino boards (brain of the system) I have analog tiny camera with microphone, actually this camera has built-in 2.4Ghz transmitter too, so this is going to be on my robot and receiver will display video on the joypad (I'll equipt 2nd version with 262K 3.2'' color screen with touch control. Do not know if Arduino MEGA 2650 will be powerfull enough to handle streaming, but this is an idea.